Arity of Relationships
The number of entities in a relationship is the Arity of the relationship. The most common Arities are unary, binary, and ternary relationships.
Unary (Recursive) Relationship: A unary (also known as a recursive or self-referencing) relationship involves only one entity. A one-to-many recursive relationship describes a hierarchy, whereas a many-to-many relationship describes a network or graph. In a hierarchy, an entity instance has at most one parent (or higher level entity).
Binary Relationship: An Arity of two is also known as binary. A binary relationship, the most common on a traditional data model diagram, involves two entities.
Ternary Relationship: An Arity of three, known as ternary, is a relationship that includes three entities.
For Your Further Reading:
- RACI Matrix
- Big Data – Activities
- Big Data – Readiness and Risk Assessment
- Data Warehouse, Data Lake & Data Vault
- Data Centric Organization
- NoSQL Column-Oriented Database – Columnar Database
- CDO – Chief Data Officer
- DMO Alternatives and Design Considerations
- Data Governance – Core Benefits
- Data Quality – Preventive and Corrective Actions
- Oracle 19c – Clone an Existing RDBMS using Gold Image?
